1. Field of the Invention
The invention relates to sun screens for reducing intensity of sunlight flowing into an interior of a vehicle or building, and more particularly, to sun screens having reflective surfaces everywhere spaced from a curved or contoured window pane.
2. Description of the Prior Art
In hot climates, such as the Southwestern states of the United States, the sun's rays can rapidly deteriorate the interiors of automobiles. Further, the heating effect of the sun's rays within an automobile is frequently greater than the cooling capacity of automotive air conditioning units, causing considerable discomfort to the occupants during operation of the automobile. Various devices have been proposed for alleviating the above conditions. For example, venetian blinds have been mounted interior to rear windows of automobiles. However, venetian blinds are expensive, cumbersome and unattractive and further impair vision to a degree inconsistent with safe operation of a vehicle. Various types of flexible plastic retractable shades have been mounted interior to automobile windows. However, such devices are expensive, cumbersome, unattractive and easily damaged.
Accordingly, it is an object of the invention to provide a sun screen device for reducing intensity of sunlight entering a vehicle, wherein the sun screen device is less expensive, less cumbersome, and more attractive than previous venetian blind or retractable shade devices.
U.S. Pat. No. 3,698,761 discloses use of a flexible or semi-rigid colored or tinted sheet of acrylic resin cut to fit a contoured rear window of an automobile. The disclosed sheet includes integral tabs extending from the periphery of the precut resin sheet for insertion beneath a flexible flange of a window frame, causing bending of the semi-rigid sheet so that surface-to-surface contact exists along the acrylic sheet and the inner surface of the window pane. The surface of the tinted sheet intercepts or filters some of the incident sunlight. However, the filtering occurs inside the vehicle, and the tinted sheet therefore dissipates a substantial amount of heat which is subsequently conveyed to the interior portions of the vehicle by thermal conduction. Further, the temperature of the acrylic material is greatly increased, causing rapid deterioration thereof. The semi-rigid sheet of U.S. Pat. No. 3,698,761 is pressed against the window pane to prevent formation of mist on the window pane due to extreme temperature differences between inside and outside of the vehicle. However, this prevents rapid removal of heat built up in the acrylic sheet, thereby furthering deterioration of the acrylic sheet due to the excessive heat.
It is therefore another object of the invention to provide a semi-rigid sun screen device which avoids excessive buildup of heat which leads to rapid deterioration of the sun screen.
Yet another object of the invention is to provide a flexible sun screen system which allows air circulation between a window pane and a flexible sun screen to effect rapid removal of heat absorbed by the sun screen to prevent deterioration of the sun screen due to excessive heat buildup therein.
Still another object of the invention is to provide a semi-rigid sun screen which absorbs less heat than sun screens of U.S. Pat. No. 3,698,761.
The sun screen described in U.S. Pat. No. 3,698,761, once installed, is not easily removable due to the manner in which the tabs extend under the flexible frame of the window pane, causing "bowing" of the acrylic sheet into intimate surface-to-surface contact with the window pane. Removal of the acrylic sheet, especially if it has deteriorated due to excessive heat buildup, may result in damage to or destruction of the acrylic sheet which precludes further use thereof. Since it is frequently quite desirable to remove sun screens in the cooler seasons to allow more sunlight to enter a vehicle, it is highly desirable that the sun screens be easily removed.
It is therefore a further object of the invention to provide a flexible sun screen which is easily removable without damage thereto.
The flexible window frames or grommets surrounding rear windows of many automobile models are subject to variations in size. If the sun screen described in U.S. Pat. No. 3,698,761 is not precisely cut to match the inner dimensions of the inner surface of the frame-supporting grommet of a particular vehicle, there may be unattractive light leaks between the edge of the sun screen and the inner surface of the flexible grommet. Alternatively, if the dimensions of the sun screen are slightly too large, it may not be possible to install the sun screen without trimming certain portions of the sun screen edge.
It is therefore a still further object of the invention to provide a flexible sun screen which can be easily installed without precise matching of the flexible sun screen to inner dimensions of a frame or grommet supporting or surrounding a window pane.
A reflective mylar substance is frequently attached to interior surfaces of window panes by means of adhesive. However, this approach has several serious shortcomings. One is that the incident sunlight attacks the adhesive before and after being reflected by the reflective mylar. This causes rapid deterioration and discoloration of the adhesive.
Accordingly, it is a still further object of the invention to provide a reflective sun screen which avoids or reduces discoloration or chemical deterioration due to cumulative affects of ambient sunlight.
A novelty search directed to the present invention uncovered the following additional U.S. Pat. Nos. which are believed to be representative of the state of the art: 1,571,019, 2,349,470, 2,546,609, 2,625,217, 3,025,098, 3,266,560, 3,312,023, 3,868,293, 3,847,201, 2,757,040, 3,276,943 and British Pat. No. 879,130.
A yet further object of the invention is to provide a sun screen device which overcomes the shortcomings of the known prior art.